An Iranian official says the country has canceled a London conference where it was set to promote new contracts for global oil companies.

“The British Embassy in Tehran could not issue visas for representatives of Iranian companies as its visa section has yet to become active," Iran’s weekly magazine Seda quoted Ali Kardor, deputy head of the National Iranian Oil Company, as saying on January 30.

The British government did not comment.

Kardor said foreign companies will now be invited in May to bid for the new Iran Petroleum Contracts (IPCs).

The London event had been set for February 22-24.

More than 100 firms, including Britain's BP, France's Total, and Italy's Eni, attended a Tehran conference in November to hear about the IPCs.

Tehran is sweetening the terms of its oil-development contracts to attract again international companies as sanctions over Iran's nuclear program were lifted earlier this month.